Generation of light by the reaction of anhydrides of oxalic acid with a peroxide in tpresence of a fluorescer



United States Patent GENERATION OF LIGHT BY THE REACTION OF ANHYDRIDES 0F OXALIC ACID WITH A PER- OXIDE IN THE PRESENCE OF A FLUORESCER Michael McKay Rauhut, Norwalk, Conn., and Laszlo Joseph Bollyky, New York, N.Y., assignors to American Cyanamid Company, Stamford, Conn., a corporation of Maine No Drawing. Continuation-impart of application Ser. No. 425,599, Jan. 14, 1965. This application Sept. 8, 1965, Ser. No. 485,920

16 Claims. (Cl. 252-188.3)

ABSTRACT OF THE DISCLOSURE A composition for the production of chemiluminescent light, intermediate reactants which when reacted with other necessary reactants produce chemiluminescent light, and the chemiluminescent process comprising admixing reactants comprising an oxalic acid type; also, novel chemiluminescent reactant compounds.

This is a continuation-in part of application Ser. No. 425,599, filed Jan. 14, 1965, now abandoned.

The present invention relates to novel compositions of matter and reactions and to the direct generation of light from chemical energy employing such compositions. By light as referred to herein is meant electromagnetic radiation at wavelengths falling between 350 mg and 800 mg.

The art of generating light from chemical energy, i.e., chemiluminescence, is continually in search of compositions which when reacted substantially improve the intensity and lifetime of light emission as contrasted to known chemiluminescent compositions and reactions. Obviously, improved compositions are constantly in demand for use as signal devices, for area illumination, etc.

The art has known for some time that oxalyl chloride in combination with aqueous (30%) hydrogen peroxide and a fluorescent compound generates a light whose lifetime is very short (on the order of about 8 to 30 seconds) and whose intensity is of little practical utility. Numerous attempts have been made to improve this chemiluminescent composition and many others similar to it, but with little success.

According to a publication by Edward A. Chandross, (Tetrahedron Letters No. 12, pp. 761-765, 1963) the chemiluminescent reaction employing oxalyl chloride may be represented as follows:

H reaction (2) In the above reaction, a cyclic transition structure is first formed, followed by a breakdown of the ring into hydrochloric acid, carbon monoxide, oxygen, and chemical energy. It is clear that an essential mechanistic feature of the Chandross reaction, as represented by Chandross, is the splitting out of HCl from a six-membered cyclic transition state. Thus the process as described by Chandross requires the specific structure (2) since any alteration that eliminates the possibility of HCl elimination in a cyclic transition state would defeat the chemiluminescent process.

An extensive investigation which we have carried out has shown that, contrary to the teachings of Chandross, certain other oxalic acid compounds when reacted under certain conditions can unexpectedly provide chemiluminescence.

The mechanism of the oxalyl chloride reactions (as represented by Chandross) is an entirely different and distinct mechanism from that of this invention disclosed herein, as is discussed at length below. It should also be recognized that the mechanisms by which chemiluminescent light may be generated are so poorly understood that it is not possible at present to predict those structures which convey the chemiluminescent property. This is amply illustrated by the phthalhydrazide series of compounds, some of which are chemiluminescent and some of which are not chemiluminescent (see A. Bernanose, Bull. Soc. Chim. France, 17,567 (1950)).

It is an object of this invention to obtain a chemiluminescent composition and a process of employing said composition whereby a high efliciency may be obtained in the conversion of chemical energy into light.

Another object is to obtain a chemiluminescent compound which produces a light over an extended period of time.

Another object of this invention is to obtain a chemiluminescent composition which attains a light of substantially higher intensity than has been obtained with former chemiluminescent compositions.

Another object of this invention is to obtain a chemiluminescent composition which may be employed to obtain light by a process which is mechanically simple and which is economically inexpensive.

Another object of this invention is to obtain a chemiluminescent reactant which is stable over a long period of time and which may be subsequently reacted to obtain chemiluminescent light.

Another object of this invention is to obtain a chemiluminescent reactant which when reacted will obtain chemiluminescent light by a process which is not hazardous.

Another object of this invention is to obtain a chemiluminescent reactant which when employed in the presence of a fluorescent compound will produce chemiluminescent light.

Another object of this invention is to obtain a reaction product formed by the reaction of an oxalic acid type anhydride of the formula described below with a peroxide, fluorescent compound, and a diluent which may include water.

We have unexpectedly discovered that the objects of this invention are obtained by admixing (l) an oxalic acid anhydride or an oxalic acid-type anhydride, (2) a peroxide, (3) a fluorescent compound and (4) a diluent. -If conditions are not acid, water need not be added to the reaction, but the presence of a minor amount 01 water is preferred. The di-anhydrides are the preferred reactants.

The term chemiluminescent reactant, as used herein, means a mixture which will result in a chemiluminescent reaction when reacted with other necessary reactants in the process as disclosed herein.

The term chemiluminescent composition, as used herein, means a mixture which will result in chemiluminescence.

The term admixing, as used herein, means reacting or sufiiciently bringing together component reactants to obtain a chemiluminescent reaction.

The term peroxidic groups, as used herein, represents HOO, ROO, or RCOO-. R is defined in the anhydride below, but in which the R in ROOH cannot be aryl.

The term diluent, as used herein, means a solvent or vehicle which when employed with a solvent does not cause insolubility.

The term peroxide compound, as used herein, also includes compounds which upon reaction produce the peroxide group.

The term hydrogen peroxide compound includes (1) hydrogen peroxide and (2) hydrogen peroxide-producing compounds.

The anhydride compound of the oxalic acid-type suitable for use in applicants invention includes a large number of preferred dianhydride compounds in the typical formula (RCOOCO(CO), OCOR', in which R and R may be any aliphatic or aromatic groups, including halogen, or aromatically substituted compounds, for example, triphenyl substituted methyl groups and in which n is at least 1 and may be any number above 1, such as 2, 3, 7, 9, 13 etc. However, other organic oxalic acid anhydrides may also be employed. Typical examples follow.

(A) Anhydrides of the following types:

where R or R is:

(I) alkyl groups: e.g., decyl-; pentyl-; ethyl-, methyl-, iso-propyl-, cyclohexyl-, etc. or substituted alkyl groups, by substituents such as:

(a) by aromatic groups: eg triphenylmethyl-, di-

phenylmethyl-, benzyl-;

(b) by halogen: e.g., chloromethyl-, chloropentyl-,

bromobutyl-;

(c) by acyloxy group: e.g., benzoyloxyethyl-, acetoxydecyl;

(d) by carbonyl groups: e.g., formylmethyl-, propionylmethyl-;

(e) carboxyl group: e.g., carboxymethyl, carboxyethyl-;

(f) they alkoxy group: e.g., ethoxymethyl-, methoxyet yl-;

(g) by tertiary amino groups; e.g., acetylaminomethyl; methyl(phenyl sulfonyl)aminoethyl-, dimethylaminoethyl;

(h) by heterocyclic group: e.g., pyridylethyl-, furyl methyl-, tetrahydrofuryl-propyl, acridinylethyl-;

(i) by sulfo groups: e.g., sulfomethyl-;

In the above formula, either or both R and R may be hydrogen, also.

(II) Aryl groups: e.g., phenyl-, naphthyl-, or substituted aryl groups by substituents such as:

(a) by alkyl groups: e.g., toly-, ethylphenyl-;

(b) by halogen: e.g., chlorophenyl-, bromophenyl-;

(c) by acyloxy groups: e.g., benzoyloxyphenyl-;

(d) by carbonyl groups: e.g., formylphenyl-;

(e) by carboxyl groups: e.g., carboxyphenyl-;

(f) by alkoxy groups: e.g., methoxyphenyl-;

(g) by amino groups: e.g., acetylaminophenyl-, di-

ethylaminophenyl-;

(h) by heterocyclic groups: e.g., pyridylphenyl-,

tetrahydrofurylphenyl-;

(i) by sulfo groups: e.g., sulfophenyl-;

(III) Heterocyclic groups: e.g., pyridyl-, furyl-, acridinyl-, tetrahydrofuryl-, or substituted heterocyclic groups by substituents such as:

(a) by alkyl groups: e.g., methylpyridyl-;

(b) halogen: e.g., chloropyridyl-;

(c) by acyloxy groups: e.g., acetoxypyridyl-;

(d) by carbonyl groups: e.g., formylpyridyl-;

(e) by carboxyl groups: e.g., -carboxypyridyl-;

(f) by alkoxy groups: e.g., methoxyfuryl-;

(g) by amino groups: e.g., dimethylaminotetrahydrofuryl-;

(h) by sulfo groups: e.g., sulfofuryl-;

(IV) Unsaturated alkyl groups: e.g.,

ethynyl-.

(B) Other anhydrides, such as:

(a) anhydrides with dicarboxylic acids: e.g., malonic acid-, glutaric acid, adipic acid;

(b) cyclic anhydrides with dicarboxylic acid:

malonic acid-, glutaric acid-;

(c) polymeric anhydrides with dicarboxylic acids: e.g.,

malonic acid-, adipic acid;

((1) anhydrides with acids which are fluorescent: e.g., an

oxalic acid anhydride of 9-carboxy-l0-phenyl anthracene, fluorescein, 9-carboxyacridine, o-phenoxyphenylbenzoic acid, methylterephthalic acid.

vinyl-, allyl-,

For any of the above anhydrides in which R and/or R may be any of the typical substituents disclosed, n may also vary, and as stated in the above structural formula, may be 1 or more. Typical acid anhydrides include oxalic acid anhydride in which n is 1, ketomalonic acid anhydride in which n is 2, diketosuccinic acid anhydride in which n is 3, triketoglutaric acid anhydride in which n is 4, tetraketoadipic acid in which n is 5, heptaketoazelaic acid anhydride in which n is 8, undecaketobrassylic acid anhydride in which n is 12.

Typical compounds include bistriphenylaceticoxalic anhydride, triketoglutaric-oxalic anhydride, dibenzoic-oxalic anhydride, bis-(4-methoxybenzoic)-oxalic anhydride, dibenzoic-tetraketoadipic anhydride, dilauric-oxalic anhydride, dipivalic-diketosuccinic anhydride, glutaric-oxalic anhydride, bis(2,4- dimethoxybenzoic)-oxalic anhydride, etc.

It should be noted that when R and/ or R' are an acyloxy group, and when the acid anhydride is an oxalic acid anhydride, the structure of the anhydride could be as follows:

in which R" and/or R typically could be any of the above stated values for R and R. This typical compound is thus seen to introduce the concept of a chain type compound as within the scope of this invention.

Oxalic acid di-anhydrides that have produced uniform results are (l) bistriphenylacetic acid oxalic acid anhydride, (2) dilauric acid oxalic acid anhydride, and (3) bis(4-methoxy benzoic) oxalic anhydride. The bistriph'enylacetic oxalic acid, anhydride obtains the preferred results of this invention.

The peroxide employed in the compositions and process of this invention may be obtained from any suitable peroxide compound. For example, the peroxide may be employed as sodium peroxide. Alternatively, sodium perborate may be placed in aqueous solution whereby a solution of hydrogen peroxide is obtained. Obviously, hydrogen peroxide or its solution may be employed. Although the presence of water is necessary in order to obtain the chemi-luminescence in certain embodiments of this invention, the peroxide employed may be obtained from anhydrous hydrogen peroxide compounds, such as, perhydrate or urea (urea peroxide), perhydrate of pyrophosphate (sodium pyrophosphate peroxide), pyrohydrate of histidine (histidine peroxide), sodium perborate, and the like. Still another form in which the anhydrous H 0 may be provided in the composition is that of an anhydrous solution of H 0 in a suitable solvent such as an ether, an ester, an aromatic hydrocarbon, etc., of the type which would provide a suitable diluent for the composition of this invention. Whenever hydrogen peroxide is contemplated to be employed, any suitable compound may be substituted which will produce hydrogen peroxide.

The peroxide concentration may range from about 1 to 100% and may be diluted before or after mixing, though the latter is generally preferred. The acid anhydride component may be added as a solid or in admixture with a suitable solid peroxide reactant or in a suitable diluent, or alternatively dissolved directly in a solution containing the peroxide reactant.

Typical diluents Within the purview of the instant discovery are those that do not readily react with a peroxide, such as, hydrogen peroxide, and which do not readily react with the carboxylic anhydride of oxalic acid.

Because water is a necessary reactant in the production of chemiluminescent light in certain (i.e., acidic) embodiments according to the present invention, it is obvious that the water also can serve as a minor portion of the diluent. Under natural conditions, water at least under 0.1 molar concentration is preferred. The term water," as used herein, includes water-producing compounds, such as, hydrates. In addition, however, either one or more diluents may be included with or in the place of water, so long as the peroxide employed is at least partially soluble in the diluent(s), such as, for example, at least one gram of H 0 per liter of diluent. The following are illustrative of the additional diluents or solvents which may be employed: non-cyclic or cyclic ethers, such as, diethyl ether, diamyl ether, diphenyl ether, anisole, tetrahydrofuran, dioxane, and the like esters, such as, ethyl acetate, propyl formate, amyl acetate, dimethyl phthalate, diethyl phthalate, methyl benzoate, and the like; aromatic hydrocarbons, such as, benzene, xylene, toluene, and the like.

If the reaction medium contains an acid in an amount suflicient to obtain a strongly acid pH of less than about pH 3, (1) water, or (2) an alcohol (such as anhydrous ethyl alcohol) should be present to obtain an optimum chemiluminescent reaction and if water is a partial diluent, the Water may be present in an amount up to less than about 70% water, based on the total percentage of dilu ent; however, lower percentages of water are preferred.

The fluorescent compounds contemplated herein are numerous and they may be defined broadly as those which do not readily react on contact with the peroxide employed in this invention, such as, hydrogen peroxide; likewise, they do not readily react on contact with an aliphatic anhydride of oxalic acid. Typical suitable fluorescent compounds for use in the present invention are those which have a spectral emission falling between 330 millimicrons and 800 millimicrons and which are at least partially soluble in any of the above diluents, if such diluent is employed. Among these are the conjugated polycyclic aromatic compounds having at least 3 fused rings, such as: anthracene, substituted anthracene, benzanthracene, phenanthrene, substituted phenanthrene, naphthacene, substituted naphthacene, pentacene, substituted pentacene, and the like. Also included arevheterocyclic compounds, such as, tetraphenyl porphine, zinc tetraphenyl porphine, and diphenylisobenzofuran. Typical substituents for all of these are phenyl, lower alkyl, chlorine, bromine, cyano, alkoxy (C -C and other like substituents which do not interfere with the light-generating reaction contemplated herein.

Numerous other fluorescent compounds having the properties given hereinvabove are well known in the art. Many of these are fully described in Fluorescence and Phosphorescence, by Peter Ptringsheim, Interscience Publishers, Inc., New York, N.Y., 1949. While only typical fluorescent compounds are listed hereinabove, the person skilled in the art is fully aware of the fact that this invention is not so restricted and that numerous other fluorescent compounds having similar properties are contemplated for use herein.

It should be noted, however, that although a fluorescent compound is necessary to obtain the production of light,

the fluorescent compound is not necessary to obtain a chemical reaction and chemical energy release. Also, for example, a chemiluminescent anhydride, such as the oxalic acid anhydride of 9-carboxy-l0-phenyl anthracene does not require -a separate fluorescent compound to obtain light. Other typical fluorescent oxalic acid anhydrides include (1) l-carboxyacridine, (2) rubrene-2-car-boxylic acid, (3) anthracene-l-carboxylic acid, and (4) 1,3-bis- (4-carboxyphenyl) isobenzofuran.

It has been found that the molar (moles per liter of diluent) concentrations of the major components of the novel composition herein described may vary considerably. It is only necessary that components be in sufiicient concentration to obtain chemiluminescence. The anhydride of oxalic acid concentration normally is in the range of at least about 10'', preferably in the range of at least about 10- to about 1 molar; the fluorescent compound is present in the range of from about l0 to 5, preferably 10* to l0 molar; under acidic conditions the water or an alcohol must be present in an amount suflicient to initiate the neaction; and the diluent must be present in a suflicient amount to form a solution of the reactants involved in the chemiluminescent reaction. There is no known maximum limit on the concentration of anhydride employed in the reaction.

One typical embodiment of this invention involves the use of two separate liquid phases in a single container where one phase contains the anhydride of this invention and the other phase contains hydrogen peroxide, and either phase contains a fluorescent compound. In this embodiment reaction takes place at the interface [between phases. A typical example would be the use of solution of anhydride and fluorescer in dimethylphthalate and an aqueous solution of hydrogen peroxide. It is within the scope of this invention to use other combinations of miscible and particularly immiscible solvents.

Another typical embodiment of this invention involves the use of a solvent having poor solution capacity for the anhydride so that a substantial quantity of the anhydride rem-ains undissolved initially. Similarly, other solvents could be employed in which some other necessary reactant is insoluble.

The chemiluminescent composition of this invention which obtains chemiluminescent light emission upon the admixing of the ingredients of the composition, may be ia'drnixed in a single stage of admixing or in a sequence of steps of admixing the separate ingredients. Accordingly, alternative compositions may be prepared which may be stored over a period of time and which may :be admixed with the final ingredients rat a time when the chemiluminescent lighting is desired. For example, one such composition would be a composition which includes an oxalic acid anhydride and a fluorescent compound, but which does not include a peroxide compound and does not include water. Another example would be a composition which includes an oxalic acid anhydride, a fluonescer, and a perborate, but which does not include water. An alternative composition would be a composition which includes oxalic acid anhydride, a fluorescent compound, and a waterbound compound such as a stable hydrate such as magnesium sulfate hydrate, but which does not include a peroxide compound. Obviously, the preferred compositions which would be less than all necessary components to produce a chemiluminescent light, would be a composition which 'would be substantially stable to a practical degree over an extended period of time; otherwise, there would be no real advantage in forming a chemiluminescent reactant to be employed in a subsequent chemiluminescent reaction.

The wavelength of the light emitted by chemiluminescence of the compositions of this invention, i.e., the color of the light emitted, may be varied by the addition of any one or more energy transfer agents (fluorescers) such as the known fluorescent compounds discussed at length above.

The wavelength of the light emitted by the composition of this invention will vary, depending upon the particular fluorescent component employed in the reaction.

Although in the process of obtaining chemiluminescent light according to this invention, it is normally not necessary to employ a specific order of sequence of steps in the adding of the individual ingredients of the inventive chemiluminescent composition; it has been found (1) that each of the above objects are achieved to an unexpectedly superior degree when the peroxide compound is added and admixed subsequent to the admixing of all other necessary ingredients, (2) that in the embodiment in which water is included and in which the mixture is alkaline, the anhydride must be added before water addition in order to obtain chemilu-minescene, and (3) the fluorescent component preferably should be already in the reaction mixture at the time of addition of the last component necessary to bring about the chemical reaction and the concurrent release of chemical energy.

Additionally, it has been found that the superior intensity of chemiluminescence is obtained when the final mixture producing the luminescence is maintained at a temperature of \between about 40 C. and 75 C., preferably between about 20 C. and 50 C.; however, the luminescence of applicants process is not limited to these ranges. However, temperature is not critical.

Additionally, the composition and the process which obtain preferred results has a pH of about pH 3 or more, whereby the above objects of the invention are achieved to a highly superior degree.

A wide variety of organic and inorganic acids is contemplated, typical acids being: .alkane sulfonic acids, such as methane sulfonic acid, ethane sulfonic acid, butane sulfonic acid, and the like; aromatic sulfonic acid such as benzene sulfonic acid, para-toluene sulfonic acid, phenyl sulfonic acid, and the like; trifluoracetic acid; mineral acids such as HCl, HNO H 50 and purophosphoric; Lewis acids, including AlCl etc.; perchloric acid, boron-trifluoride; organophosphorus acids, such as, phenylphosphonic acid, and the like; etc.

The following oxalic acid anhydrides are novel chemiluminescent compounds: a compound of the formula:

OO 0 II II II II RCOCCOCR' in which R and R are each a substituent selected from the group consisting of non-substituted-aryl, arylmethyl, diarylmethyl, triarylmethyl, alkylaryl, alkoxyaryl, sulfoaryl, carboxyaryl, arylaryl, and aryloxyaryl substituents, where typical substituted aryl substituents include methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, tetramethoxyphenyl, pentamethoxyphenyl, alkylphenyl, and polyalkylphenyl.

In the practice of the above process, to obtain chemiluminescent light, a peroxide such as hydrogen peroxide reacts With the aliphatic anhydride of an oxalic acid to produce an intermediate compound in which a peroxide group replaces an aliphatic acid group (RCOO) adjacent to an oxygen substituted carbon atom, said peroxide-substituted product being capable of further reaction to produce chemiluminescence in the presence of fluorescer.

A subsequent intermediate second reaction takes place by the reaction of the first formed (singly substituted) intermediate reacting with water whereby at least one remaining aliphatic acid group (RCOO) adjoining an oxygen substituted carbon reacts to obtain a second intermediate reaction product in which the reacting aliphatic group is replaced by a hydroxy group to form an acid. Alternatively, a peroxide other than hydrogen peroxide may resort in the second step to give a diperoxyoxalate. The mechanism of applicants invention, i.e., the reactions and iii HOOCCOI-I Fluorescer Chemiluminescence (2) Second intermediate reaction:

II II [I H ll [HOOCCOCR] 1120 [HOOOOOH] II III 3) A third reaction subsequently takes place in which the second intermediate Compound III breaks down thereby releasing chemical energy, according to the following reaction:

ll ll [HO/OC/CO/H] H1O 20 O: chemical energy III If any one or more of the fluorescent compounds (discussed above) is present, each fluorescent compound absorbs chemically released energy, and subsequently activated compound(s) release(s) energy in the form of light, known as chemiluminescent illumination, according to the following reactions:

Fluorescent [H O O C C O H] Compound present E 0 2001 [an activated Fluorescent Compound] (5) [Activated Fluorescent Compound]- the Fluorescent Compound-plight For the above Compound I, if an organohydroperoxide, such as t-butyl hydroperoxide, is substituted for the above hydrogen peroxide, the reaction product would be a compound of the typical Formula IV 0 00 1M") 0 J (J o 0 R a monocarboxylic acid anhydride of a monoperoxyester of oxalic acid, in which R can be solely an alkyl, and in which R is H, or alkyl, or aryl.

Similarly, if a peroxycarboxylic acid, such as peroxylauric acid, is reacted with the above Compound I, a re action product of the typical formula o oo 0 I! H H H RCOCCOOCR in which both Rs may be H or alkyl or aryl-a monocarboxylic acid anhydride of a monoacylor monoarylperoxy-oxalic acid.

Under conditions where water is a reactant, as least part of the light emission is derived from the decomposition of monoperoxyoxalic acid, which is derived from the reaction of hydrogen peroxide with a monocarboxylic anhydride of oxalic acid according to the following mechamsm:

The above Compounds II, III, IV, V, and VI are new compounds. Also, the Compound VI (a monoanhydride 9. of oxalic acid) illustrates that the scope of this invention includes the employment of monoanhydrides of the oxalic acid-type.

It is clear that no apparent relationships exist between the mechanism of this invention, as represented above, and the mechanism of oxalyl chloride as represented by Chandross, discussed above at length. Moreover, as is evident from the examples below, the chemiluminescent intensity and lifetime of light emission from the process disclosed herein are both markedly superior to the intensity and lifetime of the Chandross process.

Although the above reactions are believed to be the mechanism by which applicants invention produces chemiluminescent light, the invention disclosed herein is not to be restricted to this theory, except as limited in the appended claims.

Within the broad generic invention in which oxalic acid anhydrides having chemiluminescent properties when reacted with a peroxide compound and diluent is disclosed, there are subgeneric inventions as follows:

Where the reaction of the oxalic acid anhydride is carried out in an acidic pH, it was unexpectedly discovered that water must be pressent in an amount up to about less than 70% of the solvent employed. Moreover, only peroxides which would ultimately produce hydrogen peroxides (H work in aqueous media employing an acid.

Peroxide compounds which do not work when the anhydride reaction takes place in acidic media, include peroxide compounds, such as, perbenzoic acid, benzoyl peroxide, perlauric acid, di-t-butyl peroxide and t-butyl hydroperoxide.

When the anhydride is reacted under near neutral or alkaline (basic) conditions, at a pH above about pH 4.5, it has been unexepectedly found that the reaction media may be anhydrous; however, a small amount of water is preferred. Under neutral or alkaline conditions, it has been found that peroxides which work include peroxide compounds, such as, hydrogen peroxide, perbenzoic acid, benzoyl peroxide, perlauric acid, and t-butyl hydroperoxide. However, di-t-butyl peroxide does not work in the anhydrous state, under alkaline reaction conditions.

Pursuant to the present invention, disclosed herein, very intense light is generated and the light emissions last anywhere from about 16 to 60 times longer than that of the art-known aqueous compositions described hereinbefore, such as oxalyl chloride.

The following examples are intended to illustrate the present invention and are in no way intended to limit the invention except as limited in the appended claims.

EMMPLES The anhydrides of oxalic acid prepared for and used in the test experiments below are as follows:

A. Bistriphenylacetic acid oxalic acid anhydride n u Ii 1? Ii (CoH)sCC-O-CCOCC(CuHrJa B. Diacetic acid oxalic acid anhydride 0 0 0 o H H II II OHaCOC-COCCH3 C. Dilauric acid oxalic acid anhydride i i i u CuHz3CO-C-CO C-C11Hz D. Bis-4-methoxybenzoic-oxalic anhydride B. and D. exhibit a preferred degree of chemiluminescence, and D. additionally exhibits a preferred degree of thermal stability. However, A. through D. are each superior to random compounds such as dibenzoic acid oxalic acid anhydride.

10 EXAMPLE 1,

Approximately 3 mg. compound A is added to 5 ml. solution of 1 mg. 9,10-diphenylanthracene and 0.25 ml. water in 1,2-dimethoxyethane (glyme) maintained at a temperature of 2530 C. No peroxide compound was employed. No chemiluminescence is observed.

EXAMPLE H (a) hydrogen peroxide H 0 (b) perbenzoic acid C 0H5 C 0 O H (c) benzoylperoxide (d) peroxylauric acid it CuHza C O OH (e) di-t-butyl peroxide C H OOC H (f) t-butyl hydroperoxide C H OOH EXAMPLE III Approximately 3 mg. compound A is added to a 5 ml. solution of 1 mg. 9,10-diphenylanthracene, 0.25 ml. water (optional) and 0.5 ml. aqueous hydrogen peroxide (peroxide (a)) in 1,2-dimethoxyethane (glyme) maintained at a reaction temperature of 2025' C. No acid and no base is added. A strong blue light is emitted for several minutes on the addition of compound A to the solution. Strong chemiluminescent light emission is obtained when no water is added and also when peroxide is anhydrous H 0 or 30% aqueous H 0 Thus, chemiluminescence is obtained when water is present, without either acid or base being added.

EXAMPLE IV Approximately 3 mg. compound A is added to a 5 ml. solution of 1 mg. 9,10-diphenylanthracene and 0.3 ml. anhydrous hydrogen peroxide in glyme maintained at a reaction temperature of 10-15 C. Strong blue light is emitted for several minutes.

Thus, chemiluminescence is obtained in the absence of water without the addition of either acid or base.

EXAMPLE V EXAMPLE VI Approximately 3 mg. compound A is added to a 5 ml. solution of 1 mg. 9,10-diphenylanthracene, 0.2 ml. methanesulfonic acid, 0.25 ml. water and about 15 mg. t-butyl hydroperoxide (peroxide F) in glyme maintained at a reaction temperature of 2530 C. No chemiluminescence is observed.

11 The results are identical with peroxides as follows:

Identical results are obtained with peroxide (f) at a reaction temperature of 5 C.

Strong chemiluminescence is observed for 15-20 minutes when peroxide (a) (above) is employed.

(a) when compound A, B, C, or D are used;

(b) when compound A was used with rubrene in the place of 9,10-diphenylanthracene;

() when compound A is used with rubrene or with 9,10-

diphenylanthracene, at 60 C.

EXAMPLE VII Approximately 3 mg. compound A is added to a ml. solution of 1 mg. 9,10-diphenylanthracene, 0.2 g. KOH and 0.3 ml. anhydrous hydrogen peroxide in anhydrous glyme while the reaction temperature was maintained at 2530 C. Very bright chemiluminescence is observed which lasted for 5-10 minutes.

Thus, chemiluminescence was obtained in the absence of water when base is present during the reaction.

Essentially similar results are obtained with peroxides as follows: (a), (b), (c), (d), (f). Note that peroxide (e) fails to produce chemiluminescence.

The addition of 1-2 ml. water to the emitting solution quenched the chemiluminescence.

Thus, under alkaline conditions, the presence of a substantial amount of water defeats the chemiluminescent reaction.

EXAMPLE VIII Approximately 3 mg. of compound A is added to a 5 ml. solution of 1 mg. 9,10-diphenylanthracene, 0.3 ml. water, 0.2 g. KOH and about 15 mg. t-butylhydroperoxide in glyme while the reaction temperature is maintained at 65-70 C. no chemiluminescence is observed.

The result is identical when peroxide (d) is used.

Thus, the conclusion based on experiments 7 and 8 may be drawn as follows: (1) even small amounts of water present under alkaline conditions prevents the chemiluminescent reaction if the addition of water precedes the addition of the anhydride to the reaction mixture; (2) however, if water is added subsequent to the addition of anhydride to the reaction mixture, substantial amounts of water are required to defeat the chemiluminescent reaction.

EXAMPLE IX First 1 mg. 9,10-diphenylanthracene, then approximately 4 mg. compound A are added to a solution of 4 ml. tetrahydrofuran, 6 ml. water, 0.3 ml. 90% aqueous hydrogen peroxide and 0.2 ml. methane sulfonic acid. Blue light is emitted on addition of compound A to the reaction mixture. Thus, water may be used as solvent for the chemiluminescent reaction.

EXAMPLE X The light emission from a 3.0 ml. of a solution of observed that light emission continued for a period exceeding 30 minutes and that the light intensity remained above one-half its maximum value for a period of about 7 minutes. The quantum efficiency of the system based on the moles of anhydride use was calculated to be about ll.8 10 Einsteins mole This efi'iciency compares favorably to quantum yields of light reported for previously known chemiluminescent reactions such as the luminol-hydrogen peroxide-sodium hypochlorite system which has been reported to have an efiiciency of 2 10 Einsteins mole" (T. Brenner, Bull. Soc. Chim. Belges, 62, 569 (1953)). If bistriphenylacetic-oxalic acid anhydride is replaced by oxalyl chloride under the above conditions, less than one-half as much light is obtained, the intensity remains above one-half its maximum value for less than 2 minutes, and the emission is essentially extinguished after about 5 minutes. Thus, carboxylic acidoxalic acid anhydrides are substantially superior to oxalyl chloride with regard to lifetime and to light output.

This example corresponds to Example III above, except no water is employed and the reaction is here carried out at 20 C.

EXAMPLES XI-XVI Example III is repeated for each of these examples, replacing the oxalic acid-type anhydride with an anhydride not having the typical oxalic acid structure, as follows:

XI: (I? (H) C HaC 0 C C II; acetic anhydride XII:

O O 0 O C Hai 0 Q3 CHZi J 0%0113 diacetic malouic anhydride XIII: O

C sHfl i 0 (i C 5115 benzoic anhydride For each of these examples, no chemiluminescence is obtained. These examples therefore demonstrate that anhydrides of the non-oxalic acid type fail to obtain the chemiluminescence of this invention.

EXAMPLE XVII The quantum yield of chemiluminesence of the triphenylacetic oxalic anhydride-hydrogen peroxide-diphenyl-anthracene system was measured by the use of a spectroradiometer-fluorimeter. The glass stoppered cell used for the measurement held 3 ml. solution, had a 1 cm. thickness and enclosed a magnetic stirrer for agita- 5.67 10 molar bistriphenylacetic-oxalic anhydride, tion.

QUANTUM YIELD OF CHEMILUMINESCENCE Bistriphenyl-acetic oxalic Hydrogen 9,10-diphenyl- Quantum Maximum tmI anhydride mole/1 peroxide, anthracene, Solvent Yield, Emlight intenminutes mole/1 mole/1 stein/mole of sity, foot anhydride lambert (1) 5.67X10- 0.05 5X10- Dimethyl phthalate 11. 8X10- 0.07 34 (2) 4.94X10- 0.25 1 10- Benzene-dimethyl- 0. 199 10- 0. 11 7 phthalate (6-4 by volume). (3) 4.94Xl0' 0.25 1X10 d0 1 23 I0- 0. 69 11 Time required for the light intensity to decrease to one'fourth of its maximum value. At the beginning of the measurement some water was added to render the solution approximately 1.83 molar in water. Although not all of the water dissolved, it was finely dispersed in the solution due to the excellent agitation.

0.05 molar hydrogen peroxide, and 5 l0 molar 9,10- Therefore, Example 17 indicates both that a highly diphenylanthracene in anhydrous dimethyl phthalate was efficient chemiluminescent system may be obtained by the measured quantitatively with a spectrofluorimeter. It was use of bistriphenyl acetic oxalic anhydride (see No. (1)

of the above table, the No. (1) being the previously described Example X), as well as that the chemiluminescent efiiciency may be improved by the addition of water (No. (3) containing water as compared to No. (2) without added water).

It is within the scope of this invention to make such modifications of the compositions and processes disclosed herein as would be obvious to a person of ordinary skill in this art, and it is to be understood that the examples illustrating this invention are intended to limit the invention only insofar as is stated in the specification and as the following claims are limited. Also, it is within the scope of this invention to form an apparatus such as a container such as (1) an insoluble or (2) dissolvable capsule in which the reactant of this invention is enclosed for subsequent reaction with the other ingredients of this invention.

We claim:

1. A chemiluminescent reactant comprising an oxalic acid-type anhydride of the formula:

wherein Y and Y are anhydride forming groups, and n is a number at least 1, and at least one additional ingredient necessary to produce chemiluminescent light selected from the group consisting of fluorescers and peroxide compounds.

2. A chemiluminescent reactant comprising an oxalic acid-type anhydride as in claim 1 and a fluorescent compound.

3. A chemiluminescent reactant as in claim 1 comprising afluorescent oxalic acid-type anhydride as in claim 1.

4. A solid chemiluminescent reactant comprising solid ingredients comprising an oxalic acid-type anhydride as in claim 1, a peroxide compound and a fluorescent compound.

5. A chemiluminescent composition comprising an oxalic acid-type anhydride as in claim 1, a peroxide compound, a fluorescent compound and a diluent.

6. A chemiluminescent composition comprising a hydrogen peroxide compound, an oxalic acid-type anhydride as in claim 1, a diluent comprising water, and a minor amount of acid sufficient to obtain an acid pH.

7. A chemiluminescent composition comprising an oxalic acid-type anhydride as in claim 1, a peroxide compound, a diluent, and a minor amount of base sufiicient to obtain an alkaline pH.

8. A chemiluminescent composition comprising bis-triphenylacetic acid oxalic acid anhydride, a solution of a fluorescent compound in a diluent and a peroxide compound.

9. A chemiluminescent composition comprising an oxalic acid-type anhydride as in claim 1, a peroxide compound, an organic diluent, and a fluorescent polycyclic aromatic hydrocarbon.

10. A chemiluminescent process comprising admixing reactants comprising an oxalic acid-type anhydride as in claim 1, a peroxide compound, and a diluent, said reactants including at least one fluorescer.

11. A chemiluminescent process comprising admixing reactants comprising a fluorescent oxalic acid-type anhydride as in claim 1, a peroxide compound and a diluent.

12. A chemiluminescent process comprising admixing reactants comprising an oxalic acid-type anhydride as in claim 1, a fluorescent compound, and a peroxide compound, a diluent, and a minor amount of base.

13. A chemiluminescent process comprising admixing reactants comprising an oxalic acid-type anhydride as in claim 1, a fluorescent compound, a hydrogen peroxide compound, a diluent comprising water and suflicient acid to obtain an acid pH.

14. A chemiluminescent composition comprising (1) an anhydride of oxalic acid and an aromatic carboxylic acid, (2) a hydrogen peroxide compound and (3) a diluent, said composition including at least one organic fluorescent compound.

15. A chemiluminescent composition comprising (1) an anhydride of oxalic acid and a phenyl-substituted acetic acid, (2) a hydrogen peroxide compound and (3) a diluent, said composition including at least. one organic fluorescent compound.

16. A chemiluminescent reactant comprising an oxalic acid-type anhydride, as in claim 1, a fluorescent compound, and a diluent.

References Cited UNITED STATES PATENTS 2,420,286 5/ 1947 Lacey et a1. 252-1883 LEON D. ROSDOL, Primary Examiner.

J. D. WELSH, Assistant Examiner. 

